There is a nice, long road in a particular part of the UK which was once in the "open air". One day, the Department of Transport decided that, for the safety of all concerned, the road should go through a tunnel instead. So now one particular section the road, unchanged from its original course, goes through an artificial hill.

Explain, using "yes/no" questions, why they went to all that expense.

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You know what I did before I married Mrs Worrier? Anything I wanted to.

Okay, this doesn't really involve a river but near me there is a stretch of road going up into the mountains. At one point it was covered in a shed to prevent the snow from closing the road. Could it be that?

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BobBe kind, for everyone you meet is fighting a hard battle.